Diagnostic Modes

Service Mode Operation:

Snap Shot Mode Operation:

NOTE: For referrals to any chart not included in DIAGNOSTIC CHARTS, refer to COMPUTERIZED ENGINE CONTROLS.

To enter diagnostic mode, proceed as follows:

1. Turn ignition "ON".

2. Depress the "OFF" and "WARMER" buttons on the Climate Control Panel simultaneously and hold until all display panel segments illuminate which indicates the beginning of the diagnostic readout. The purpose of illuminating the two display panels is to check that all segments of the displays are working. If any of the segments are inoperative, the affected display panel will need to be diagnosed.

3. After the segment check, any trouble code stored in computer memory will be displayed on the "Data Center." These trouble codes will appear prefixed with an "E" for ECM/PCM codes, or "B" for BCM codes, or "R" for SIR codes, to designate which computer detected the malfunction. The codes will be followed by an "H" (history) if the code is intermittent, or a "C" (current) if it is a hard code. If any trouble codes are displayed or if diagnostics cannot be entered, refer to the SELF-DIAGNOSTIC CIRCUIT CHECK for the proper diagnostic procedure. If no codes are present for a system, a "NO X CODE" message (with X being the system, i.e. ECM/PCM, BCM, or SIR) will be displayed. If the communication line to a component is not operating, a "NO X DATA" message will be displayed, indicating that the BCM could not communicate with that system.

4. To view ECM/PCM DATA PARAMETERS, refer to BASIC OPERATION under COMPUTERIZED ENGINE CONTROLS/CADILLAC PORT FUEL INJECTION/DIAGNOSIS AND TESTING PROCEDURES/TESTING PROCEDURES/ECM/PCM DISPLAYS.

5. To get out of the diagnostic mode, depress the "RESET" button or turn the ignition switch OFF for 10 seconds. Trouble codes are not erased when this is done. The temperature setting will reappear in the display panel.